drivers/video/backlight/pwm_bl.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Simple PWM based backlight control, board code has to setup
   4  * 1) pin configuration so PWM waveforms can output
   5  * 2) platform_data being correctly configured
   6  */
   7
   8 #include <linux/delay.h>
   9 #include <linux/gpio/consumer.h>
  10 #include <linux/module.h>
  11 #include <linux/kernel.h>
  12 #include <linux/init.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/fb.h>
  15 #include <linux/backlight.h>
  16 #include <linux/err.h>
  17 #include <linux/pwm.h>
  18 #include <linux/pwm_backlight.h>
  19 #include <linux/regulator/consumer.h>
  20 #include <linux/slab.h>
  21
  22 struct pwm_bl_data {
  23         struct pwm_device       *pwm;
  24         struct device           *dev;
  25         unsigned int            lth_brightness;
  26         unsigned int            *levels;
  27         bool                    enabled;
  28         struct regulator        *power_supply;
  29         struct gpio_desc        *enable_gpio;
  30         unsigned int            scale;
  31         bool                    legacy;
  32         unsigned int            post_pwm_on_delay;
  33         unsigned int            pwm_off_delay;
  34         int                     (*notify)(struct device *,
  35                                           int brightness);
  36         void                    (*notify_after)(struct device *,
  37                                         int brightness);
  38         int                     (*check_fb)(struct device *, struct fb_info *);
  39         void                    (*exit)(struct device *);
  40 };
  41
  42 static void pwm_backlight_power_on(struct pwm_bl_data *pb)
  43 {
  44         struct pwm_state state;
  45         int err;
  46
  47         pwm_get_state(pb->pwm, &state);
  48         if (pb->enabled)
  49                 return;
  50
  51         err = regulator_enable(pb->power_supply);
  52         if (err < 0)
  53                 dev_err(pb->dev, "failed to enable power supply\n");
  54
  55         state.enabled = true;
  56         pwm_apply_state(pb->pwm, &state);
  57
  58         if (pb->post_pwm_on_delay)
  59                 msleep(pb->post_pwm_on_delay);
  60
  61         if (pb->enable_gpio)
  62                 gpiod_set_value_cansleep(pb->enable_gpio, 1);
  63
  64         pb->enabled = true;
  65 }
  66
  67 static void pwm_backlight_power_off(struct pwm_bl_data *pb)
  68 {
  69         struct pwm_state state;
  70
  71         pwm_get_state(pb->pwm, &state);
  72         if (!pb->enabled)
  73                 return;
  74
  75         if (pb->enable_gpio)
  76                 gpiod_set_value_cansleep(pb->enable_gpio, 0);
  77
  78         if (pb->pwm_off_delay)
  79                 msleep(pb->pwm_off_delay);
  80
  81         state.enabled = false;
  82         state.duty_cycle = 0;
  83         pwm_apply_state(pb->pwm, &state);
  84
  85         regulator_disable(pb->power_supply);
  86         pb->enabled = false;
  87 }
  88
  89 static int compute_duty_cycle(struct pwm_bl_data *pb, int brightness)
  90 {
  91         unsigned int lth = pb->lth_brightness;
  92         struct pwm_state state;
  93         u64 duty_cycle;
  94
  95         pwm_get_state(pb->pwm, &state);
  96
  97         if (pb->levels)
  98                 duty_cycle = pb->levels[brightness];
  99         else
 100                 duty_cycle = brightness;
 101
 102         duty_cycle *= state.period - lth;
 103         do_div(duty_cycle, pb->scale);
 104
 105         return duty_cycle + lth;
 106 }
 107
 108 static int pwm_backlight_update_status(struct backlight_device *bl)
 109 {
 110         struct pwm_bl_data *pb = bl_get_data(bl);
 111         int brightness = backlight_get_brightness(bl);
 112         struct pwm_state state;
 113
 114         if (pb->notify)
 115                 brightness = pb->notify(pb->dev, brightness);
 116
 117         if (brightness > 0) {
 118                 pwm_get_state(pb->pwm, &state);
 119                 state.duty_cycle = compute_duty_cycle(pb, brightness);
 120                 pwm_apply_state(pb->pwm, &state);
 121                 pwm_backlight_power_on(pb);
 122         } else {
 123                 pwm_backlight_power_off(pb);
 124         }
 125
 126         if (pb->notify_after)
 127                 pb->notify_after(pb->dev, brightness);
 128
 129         return 0;
 130 }
 131
 132 static int pwm_backlight_check_fb(struct backlight_device *bl,
 133                                   struct fb_info *info)
 134 {
 135         struct pwm_bl_data *pb = bl_get_data(bl);
 136
 137         return !pb->check_fb || pb->check_fb(pb->dev, info);
 138 }
 139
 140 static const struct backlight_ops pwm_backlight_ops = {
 141         .update_status  = pwm_backlight_update_status,
 142         .check_fb       = pwm_backlight_check_fb,
 143 };
 144
 145 #ifdef CONFIG_OF
 146 #define PWM_LUMINANCE_SHIFT     16
 147 #define PWM_LUMINANCE_SCALE     (1 << PWM_LUMINANCE_SHIFT) /* luminance scale */
 148
 149 /*
 150  * CIE lightness to PWM conversion.
 151  *
 152  * The CIE 1931 lightness formula is what actually describes how we perceive
 153  * light:
 154  *          Y = (L* / 903.3)           if L* ≤ 8
 155  *          Y = ((L* + 16) / 116)^3    if L* > 8
 156  *
 157  * Where Y is the luminance, the amount of light coming out of the screen, and
 158  * is a number between 0.0 and 1.0; and L* is the lightness, how bright a human
 159  * perceives the screen to be, and is a number between 0 and 100.
 160  *
 161  * The following function does the fixed point maths needed to implement the
 162  * above formula.
 163  */
 164 static u64 cie1931(unsigned int lightness)
 165 {
 166         u64 retval;
 167
 168         /*
 169          * @lightness is given as a number between 0 and 1, expressed
 170          * as a fixed-point number in scale
 171          * PWM_LUMINANCE_SCALE. Convert to a percentage, still
 172          * expressed as a fixed-point number, so the above formulas
 173          * can be applied.
 174          */
 175         lightness *= 100;
 176         if (lightness <= (8 * PWM_LUMINANCE_SCALE)) {
 177                 retval = DIV_ROUND_CLOSEST(lightness * 10, 9033);
 178         } else {
 179                 retval = (lightness + (16 * PWM_LUMINANCE_SCALE)) / 116;
 180                 retval *= retval * retval;
 181                 retval += 1ULL << (2*PWM_LUMINANCE_SHIFT - 1);
 182                 retval >>= 2*PWM_LUMINANCE_SHIFT;
 183         }
 184
 185         return retval;
 186 }
 187
 188 /*
 189  * Create a default correction table for PWM values to create linear brightness
 190  * for LED based backlights using the CIE1931 algorithm.
 191  */
 192 static
 193 int pwm_backlight_brightness_default(struct device *dev,
 194                                      struct platform_pwm_backlight_data *data,
 195                                      unsigned int period)
 196 {
 197         unsigned int i;
 198         u64 retval;
 199
 200         /*
 201          * Once we have 4096 levels there's little point going much higher...
 202          * neither interactive sliders nor animation benefits from having
 203          * more values in the table.
 204          */
 205         data->max_brightness =
 206                 min((int)DIV_ROUND_UP(period, fls(period)), 4096);
 207
 208         data->levels = devm_kcalloc(dev, data->max_brightness,
 209                                     sizeof(*data->levels), GFP_KERNEL);
 210         if (!data->levels)
 211                 return -ENOMEM;
 212
 213         /* Fill the table using the cie1931 algorithm */
 214         for (i = 0; i < data->max_brightness; i++) {
 215                 retval = cie1931((i * PWM_LUMINANCE_SCALE) /
 216                                  data->max_brightness) * period;
 217                 retval = DIV_ROUND_CLOSEST_ULL(retval, PWM_LUMINANCE_SCALE);
 218                 if (retval > UINT_MAX)
 219                         return -EINVAL;
 220                 data->levels[i] = (unsigned int)retval;
 221         }
 222
 223         data->dft_brightness = data->max_brightness / 2;
 224         data->max_brightness--;
 225
 226         return 0;
 227 }
 228
 229 static int pwm_backlight_parse_dt(struct device *dev,
 230                                   struct platform_pwm_backlight_data *data)
 231 {
 232         struct device_node *node = dev->of_node;
 233         unsigned int num_levels = 0;
 234         unsigned int levels_count;
 235         unsigned int num_steps = 0;
 236         struct property *prop;
 237         unsigned int *table;
 238         int length;
 239         u32 value;
 240         int ret;
 241
 242         if (!node)
 243                 return -ENODEV;
 244
 245         memset(data, 0, sizeof(*data));
 246
 247         /*
 248          * These values are optional and set as 0 by default, the out values
 249          * are modified only if a valid u32 value can be decoded.
 250          */
 251         of_property_read_u32(node, "post-pwm-on-delay-ms",
 252                              &data->post_pwm_on_delay);
 253         of_property_read_u32(node, "pwm-off-delay-ms", &data->pwm_off_delay);
 254
 255         /*
 256          * Determine the number of brightness levels, if this property is not
 257          * set a default table of brightness levels will be used.
 258          */
 259         prop = of_find_property(node, "brightness-levels", &length);
 260         if (!prop)
 261                 return 0;
 262
 263         data->max_brightness = length / sizeof(u32);
 264
 265         /* read brightness levels from DT property */
 266         if (data->max_brightness > 0) {
 267                 size_t size = sizeof(*data->levels) * data->max_brightness;
 268                 unsigned int i, j, n = 0;
 269
 270                 data->levels = devm_kzalloc(dev, size, GFP_KERNEL);
 271                 if (!data->levels)
 272                         return -ENOMEM;
 273
 274                 ret = of_property_read_u32_array(node, "brightness-levels",
 275                                                  data->levels,
 276                                                  data->max_brightness);
 277                 if (ret < 0)
 278                         return ret;
 279
 280                 ret = of_property_read_u32(node, "default-brightness-level",
 281                                            &value);
 282                 if (ret < 0)
 283                         return ret;
 284
 285                 data->dft_brightness = value;
 286
 287                 /*
 288                  * This property is optional, if is set enables linear
 289                  * interpolation between each of the values of brightness levels
 290                  * and creates a new pre-computed table.
 291                  */
 292                 of_property_read_u32(node, "num-interpolated-steps",
 293                                      &num_steps);
 294
 295                 /*
 296                  * Make sure that there is at least two entries in the
 297                  * brightness-levels table, otherwise we can't interpolate
 298                  * between two points.
 299                  */
 300                 if (num_steps) {
 301                         if (data->max_brightness < 2) {
 302                                 dev_err(dev, "can't interpolate\n");
 303                                 return -EINVAL;
 304                         }
 305
 306                         /*
 307                          * Recalculate the number of brightness levels, now
 308                          * taking in consideration the number of interpolated
 309                          * steps between two levels.
 310                          */
 311                         for (i = 0; i < data->max_brightness - 1; i++) {
 312                                 if ((data->levels[i + 1] - data->levels[i]) /
 313                                    num_steps)
 314                                         num_levels += num_steps;
 315                                 else
 316                                         num_levels++;
 317                         }
 318                         num_levels++;
 319                         dev_dbg(dev, "new number of brightness levels: %d\n",
 320                                 num_levels);
 321
 322                         /*
 323                          * Create a new table of brightness levels with all the
 324                          * interpolated steps.
 325                          */
 326                         size = sizeof(*table) * num_levels;
 327                         table = devm_kzalloc(dev, size, GFP_KERNEL);
 328                         if (!table)
 329                                 return -ENOMEM;
 330
 331                         /* Fill the interpolated table. */
 332                         levels_count = 0;
 333                         for (i = 0; i < data->max_brightness - 1; i++) {
 334                                 value = data->levels[i];
 335                                 n = (data->levels[i + 1] - value) / num_steps;
 336                                 if (n > 0) {
 337                                         for (j = 0; j < num_steps; j++) {
 338                                                 table[levels_count] = value;
 339                                                 value += n;
 340                                                 levels_count++;
 341                                         }
 342                                 } else {
 343                                         table[levels_count] = data->levels[i];
 344                                         levels_count++;
 345                                 }
 346                         }
 347                         table[levels_count] = data->levels[i];
 348
 349                         /*
 350                          * As we use interpolation lets remove current
 351                          * brightness levels table and replace for the
 352                          * new interpolated table.
 353                          */
 354                         devm_kfree(dev, data->levels);
 355                         data->levels = table;
 356
 357                         /*
 358                          * Reassign max_brightness value to the new total number
 359                          * of brightness levels.
 360                          */
 361                         data->max_brightness = num_levels;
 362                 }
 363
 364                 data->max_brightness--;
 365         }
 366
 367         return 0;
 368 }
 369
 370 static const struct of_device_id pwm_backlight_of_match[] = {
 371         { .compatible = "pwm-backlight" },
 372         { }
 373 };
 374
 375 MODULE_DEVICE_TABLE(of, pwm_backlight_of_match);
 376 #else
 377 static int pwm_backlight_parse_dt(struct device *dev,
 378                                   struct platform_pwm_backlight_data *data)
 379 {
 380         return -ENODEV;
 381 }
 382
 383 static
 384 int pwm_backlight_brightness_default(struct device *dev,
 385                                      struct platform_pwm_backlight_data *data,
 386                                      unsigned int period)
 387 {
 388         return -ENODEV;
 389 }
 390 #endif
 391
 392 static bool pwm_backlight_is_linear(struct platform_pwm_backlight_data *data)
 393 {
 394         unsigned int nlevels = data->max_brightness + 1;
 395         unsigned int min_val = data->levels[0];
 396         unsigned int max_val = data->levels[nlevels - 1];
 397         /*
 398          * Multiplying by 128 means that even in pathological cases such
 399          * as (max_val - min_val) == nlevels the error at max_val is less
 400          * than 1%.
 401          */
 402         unsigned int slope = (128 * (max_val - min_val)) / nlevels;
 403         unsigned int margin = (max_val - min_val) / 20; /* 5% */
 404         int i;
 405
 406         for (i = 1; i < nlevels; i++) {
 407                 unsigned int linear_value = min_val + ((i * slope) / 128);
 408                 unsigned int delta = abs(linear_value - data->levels[i]);
 409
 410                 if (delta > margin)
 411                         return false;
 412         }
 413
 414         return true;
 415 }
 416
 417 static int pwm_backlight_initial_power_state(const struct pwm_bl_data *pb)
 418 {
 419         struct device_node *node = pb->dev->of_node;
 420         bool active = true;
 421
 422         /*
 423          * If the enable GPIO is present, observable (either as input
 424          * or output) and off then the backlight is not currently active.
 425          * */
 426         if (pb->enable_gpio && gpiod_get_value_cansleep(pb->enable_gpio) == 0)
 427                 active = false;
 428
 429         if (!regulator_is_enabled(pb->power_supply))
 430                 active = false;
 431
 432         if (!pwm_is_enabled(pb->pwm))
 433                 active = false;
 434
 435         /*
 436          * Synchronize the enable_gpio with the observed state of the
 437          * hardware.
 438          */
 439         if (pb->enable_gpio)
 440                 gpiod_direction_output(pb->enable_gpio, active);
 441
 442         /*
 443          * Do not change pb->enabled here! pb->enabled essentially
 444          * tells us if we own one of the regulator's use counts and
 445          * right now we do not.
 446          */
 447
 448         /* Not booted with device tree or no phandle link to the node */
 449         if (!node || !node->phandle)
 450                 return FB_BLANK_UNBLANK;
 451
 452         /*
 453          * If the driver is probed from the device tree and there is a
 454          * phandle link pointing to the backlight node, it is safe to
 455          * assume that another driver will enable the backlight at the
 456          * appropriate time. Therefore, if it is disabled, keep it so.
 457          */
 458         return active ? FB_BLANK_UNBLANK: FB_BLANK_POWERDOWN;
 459 }
 460
 461 static int pwm_backlight_probe(struct platform_device *pdev)
 462 {
 463         struct platform_pwm_backlight_data *data = dev_get_platdata(&pdev->dev);
 464         struct platform_pwm_backlight_data defdata;
 465         struct backlight_properties props;
 466         struct backlight_device *bl;
 467         struct device_node *node = pdev->dev.of_node;
 468         struct pwm_bl_data *pb;
 469         struct pwm_state state;
 470         unsigned int i;
 471         int ret;
 472
 473         if (!data) {
 474                 ret = pwm_backlight_parse_dt(&pdev->dev, &defdata);
 475                 if (ret < 0) {
 476                         dev_err(&pdev->dev, "failed to find platform data\n");
 477                         return ret;
 478                 }
 479
 480                 data = &defdata;
 481         }
 482
 483         if (data->init) {
 484                 ret = data->init(&pdev->dev);
 485                 if (ret < 0)
 486                         return ret;
 487         }
 488
 489         pb = devm_kzalloc(&pdev->dev, sizeof(*pb), GFP_KERNEL);
 490         if (!pb) {
 491                 ret = -ENOMEM;
 492                 goto err_alloc;
 493         }
 494
 495         pb->notify = data->notify;
 496         pb->notify_after = data->notify_after;
 497         pb->check_fb = data->check_fb;
 498         pb->exit = data->exit;
 499         pb->dev = &pdev->dev;
 500         pb->enabled = false;
 501         pb->post_pwm_on_delay = data->post_pwm_on_delay;
 502         pb->pwm_off_delay = data->pwm_off_delay;
 503
 504         pb->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable",
 505                                                   GPIOD_ASIS);
 506         if (IS_ERR(pb->enable_gpio)) {
 507                 ret = PTR_ERR(pb->enable_gpio);
 508                 goto err_alloc;
 509         }
 510
 511         pb->power_supply = devm_regulator_get(&pdev->dev, "power");
 512         if (IS_ERR(pb->power_supply)) {
 513                 ret = PTR_ERR(pb->power_supply);
 514                 goto err_alloc;
 515         }
 516
 517         pb->pwm = devm_pwm_get(&pdev->dev, NULL);
 518         if (IS_ERR(pb->pwm) && PTR_ERR(pb->pwm) != -EPROBE_DEFER && !node) {
 519                 dev_err(&pdev->dev, "unable to request PWM, trying legacy API\n");
 520                 pb->legacy = true;
 521                 pb->pwm = pwm_request(data->pwm_id, "pwm-backlight");
 522         }
 523
 524         if (IS_ERR(pb->pwm)) {
 525                 ret = PTR_ERR(pb->pwm);
 526                 if (ret != -EPROBE_DEFER)
 527                         dev_err(&pdev->dev, "unable to request PWM\n");
 528                 goto err_alloc;
 529         }
 530
 531         dev_dbg(&pdev->dev, "got pwm for backlight\n");
 532
 533         /* Sync up PWM state. */
 534         pwm_init_state(pb->pwm, &state);
 535
 536         /*
 537          * The DT case will set the pwm_period_ns field to 0 and store the
 538          * period, parsed from the DT, in the PWM device. For the non-DT case,
 539          * set the period from platform data if it has not already been set
 540          * via the PWM lookup table.
 541          */
 542         if (!state.period && (data->pwm_period_ns > 0))
 543                 state.period = data->pwm_period_ns;
 544
 545         ret = pwm_apply_state(pb->pwm, &state);
 546         if (ret) {
 547                 dev_err(&pdev->dev, "failed to apply initial PWM state: %d\n",
 548                         ret);
 549                 goto err_alloc;
 550         }
 551
 552         memset(&props, 0, sizeof(struct backlight_properties));
 553
 554         if (data->levels) {
 555                 pb->levels = data->levels;
 556
 557                 /*
 558                  * For the DT case, only when brightness levels is defined
 559                  * data->levels is filled. For the non-DT case, data->levels
 560                  * can come from platform data, however is not usual.
 561                  */
 562                 for (i = 0; i <= data->max_brightness; i++)
 563                         if (data->levels[i] > pb->scale)
 564                                 pb->scale = data->levels[i];
 565
 566                 if (pwm_backlight_is_linear(data))
 567                         props.scale = BACKLIGHT_SCALE_LINEAR;
 568                 else
 569                         props.scale = BACKLIGHT_SCALE_NON_LINEAR;
 570         } else if (!data->max_brightness) {
 571                 /*
 572                  * If no brightness levels are provided and max_brightness is
 573                  * not set, use the default brightness table. For the DT case,
 574                  * max_brightness is set to 0 when brightness levels is not
 575                  * specified. For the non-DT case, max_brightness is usually
 576                  * set to some value.
 577                  */
 578
 579                 /* Get the PWM period (in nanoseconds) */
 580                 pwm_get_state(pb->pwm, &state);
 581
 582                 ret = pwm_backlight_brightness_default(&pdev->dev, data,
 583                                                        state.period);
 584                 if (ret < 0) {
 585                         dev_err(&pdev->dev,
 586                                 "failed to setup default brightness table\n");
 587                         goto err_alloc;
 588                 }
 589
 590                 for (i = 0; i <= data->max_brightness; i++) {
 591                         if (data->levels[i] > pb->scale)
 592                                 pb->scale = data->levels[i];
 593
 594                         pb->levels = data->levels;
 595                 }
 596
 597                 props.scale = BACKLIGHT_SCALE_NON_LINEAR;
 598         } else {
 599                 /*
 600                  * That only happens for the non-DT case, where platform data
 601                  * sets the max_brightness value.
 602                  */
 603                 pb->scale = data->max_brightness;
 604         }
 605
 606         pb->lth_brightness = data->lth_brightness * (div_u64(state.period,
 607                                 pb->scale));
 608
 609         props.type = BACKLIGHT_RAW;
 610         props.max_brightness = data->max_brightness;
 611         bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, pb,
 612                                        &pwm_backlight_ops, &props);
 613         if (IS_ERR(bl)) {
 614                 dev_err(&pdev->dev, "failed to register backlight\n");
 615                 ret = PTR_ERR(bl);
 616                 if (pb->legacy)
 617                         pwm_free(pb->pwm);
 618                 goto err_alloc;
 619         }
 620
 621         if (data->dft_brightness > data->max_brightness) {
 622                 dev_warn(&pdev->dev,
 623                          "invalid default brightness level: %u, using %u\n",
 624                          data->dft_brightness, data->max_brightness);
 625                 data->dft_brightness = data->max_brightness;
 626         }
 627
 628         bl->props.brightness = data->dft_brightness;
 629         bl->props.power = pwm_backlight_initial_power_state(pb);
 630         backlight_update_status(bl);
 631
 632         platform_set_drvdata(pdev, bl);
 633         return 0;
 634
 635 err_alloc:
 636         if (data->exit)
 637                 data->exit(&pdev->dev);
 638         return ret;
 639 }
 640
 641 static int pwm_backlight_remove(struct platform_device *pdev)
 642 {
 643         struct backlight_device *bl = platform_get_drvdata(pdev);
 644         struct pwm_bl_data *pb = bl_get_data(bl);
 645
 646         backlight_device_unregister(bl);
 647         pwm_backlight_power_off(pb);
 648
 649         if (pb->exit)
 650                 pb->exit(&pdev->dev);
 651         if (pb->legacy)
 652                 pwm_free(pb->pwm);
 653
 654         return 0;
 655 }
 656
 657 static void pwm_backlight_shutdown(struct platform_device *pdev)
 658 {
 659         struct backlight_device *bl = platform_get_drvdata(pdev);
 660         struct pwm_bl_data *pb = bl_get_data(bl);
 661
 662         pwm_backlight_power_off(pb);
 663 }
 664
 665 #ifdef CONFIG_PM_SLEEP
 666 static int pwm_backlight_suspend(struct device *dev)
 667 {
 668         struct backlight_device *bl = dev_get_drvdata(dev);
 669         struct pwm_bl_data *pb = bl_get_data(bl);
 670
 671         if (pb->notify)
 672                 pb->notify(pb->dev, 0);
 673
 674         pwm_backlight_power_off(pb);
 675
 676         if (pb->notify_after)
 677                 pb->notify_after(pb->dev, 0);
 678
 679         return 0;
 680 }
 681
 682 static int pwm_backlight_resume(struct device *dev)
 683 {
 684         struct backlight_device *bl = dev_get_drvdata(dev);
 685
 686         backlight_update_status(bl);
 687
 688         return 0;
 689 }
 690 #endif
 691
 692 static const struct dev_pm_ops pwm_backlight_pm_ops = {
 693 #ifdef CONFIG_PM_SLEEP
 694         .suspend = pwm_backlight_suspend,
 695         .resume = pwm_backlight_resume,
 696         .poweroff = pwm_backlight_suspend,
 697         .restore = pwm_backlight_resume,
 698 #endif
 699 };
 700
 701 static struct platform_driver pwm_backlight_driver = {
 702         .driver         = {
 703                 .name           = "pwm-backlight",
 704                 .pm             = &pwm_backlight_pm_ops,
 705                 .of_match_table = of_match_ptr(pwm_backlight_of_match),
 706         },
 707         .probe          = pwm_backlight_probe,
 708         .remove         = pwm_backlight_remove,
 709         .shutdown       = pwm_backlight_shutdown,
 710 };
 711
 712 module_platform_driver(pwm_backlight_driver);
 713
 714 MODULE_DESCRIPTION("PWM based Backlight Driver");
 715 MODULE_LICENSE("GPL v2");
 716 MODULE_ALIAS("platform:pwm-backlight");